1. Field of Invention
The present invention relates to light emitting diodes (LEDs). More particularly, the present invention relates to an arrangement matrix of primary color LEDs applied in the back light module of the liquid crystal display.
2. Description of Related Art
The backlight module is operated with the light of the backlight source being guided to form a planar light source by a light guiding sheet. Common backlight sources include the cold cathode fluorescent tube, the light emitting diodes (LED), etc. The cold cathode fluorescent tube dominants the market nowadays while the requirement of the LED increases gradually. Comparing with the cold cathode fluorescent tube, the LED has the advantages of the small size, the long life, the low driving voltage, the low power consumption, and the robustness against shock.
Generally speaking, the LED backlight source usually adopts the white LED directly, or the mixed white light generated from the lights of three primary colors: red, green and blue (RGB). Because of the low degree of saturation of the white light emitted by the white LED, most LED backlight modules utilized by the television sets adopt the three primary color lights (RGB) to mix and generate white light in accordance. Please refer to FIG. 1, which illustrates an arrangement matrix of primary color LEDs in the prior art. In FIG. 1, the arrangement matrix is composed of 2×2 matrixes, which is the lowest repeated matrix. As illustrated in FIG. 1, the number of green LEDs is two times of the number of the red LED and the number of the blue LED. Within the lowest matrix unit, one of the green LEDs is located at column 1, row 2, and the other is located at column 2, row 1. The red LED and the blue LED are located at column 1, row 1, and at column 2, row 2, respectively.
The aforementioned RGB arrangement matrix is the lowest repeat unit of the LED backlight source in the prior art. The number of the repeat units to compose the LED backlight source is adjusted according to the size of the required backlight source. Usually, in the backlight module, a plurality of optical diaphragms of different functions, such as a diffuse plate, a focusing sheet, etc., are adopted at a distance of 2-5 cm from the LED backlight source in order to increase the lightness of the backlight module. However, due to the limitation of the mixing distance from the LED backlight source to the optical diaphragm, as being adopted as the LED backlight source, the RGB arrangement matrix in the prior art can generate uniform white light only in the central area, but not in the circumferential area. If the mixing distance is increased further, not only the chromatic polarization is generated around the peripheral of the LED panel, but the volume of the backlight module is increased. If the mixing distance is decreased, not only the horizontal stripe chromatic polarization is generated, but the problem of chromatic polarization deteriorates at the same time. Hence, it becomes one of the most important issues to effectively mix the RGB arrangement to generate the white light, and to efficiently generate the uniform white light.
For the forgoing reasons, there is a need for a novel RGB arrangement aligning to overcome the aforementioned drawbacks.